Scientists have reported that Earth was hit by an intense, unusual burst of light that could change our understanding of the universe.
Late last year, scientists observed a 50-second burst of energy coming toward Earth, known as a gamma-ray burst, or GRB, one of the most powerful bursts in the universe. Immediately, researchers began looking for the afterglow left behind by such explosions, which could be useful in determining where the explosion came from.
But those researchers found something else instead: The explosion appeared to have come from a kilonova. Those rare events only happen when a neutron star merges with another very small object – another neutron star or a black hole.
The study challenges our understanding of where such long-lived GRBs come from. But it could provide a fascinating way to answer other questions about the universe, such as where its heavy elements come from, which is still a mystery.
And even the galaxy from which the GRB came is strange. It’s young and still forming stars — unlike the only known nearby galaxy to host such an event.
“This phenomenon appears unlike anything else we’ve seen from a long gamma-ray burst,” said Jillian Rustinejad of Northwestern University, who led the study. “Its gamma rays resemble bursts from collapsing massive stars.
Since all other confirmed neutron star mergers we have observed have been accompanied by bursts of less than two seconds, there was every reason to expect that this 50-second GRP was produced by the collapse of a massive star. This event represents an amazing paradigm shift in gamma-ray burst astronomy.”
A paper describing the findings, ‘A kilonova followed by a long-period gamma-ray burst at 350 mbs’, is published in the journal Nature Today.
The burst was first detected in December 2021 by NASA’s Neil Gehrles Swift Observatory and the Fermi Gamma-ray Space Telescope. Since then, researchers have been trying to classify the eruption and understand where it might have come from.
Among other discoveries, it showed that one event produced heavy elements weighing about 1,000 times the weight of our Earth. This suggests that kilonovae are the main source of gold production in the universe.
Because the galaxy from the GRB was relatively close, scientists were able to see it unusually well. What’s more, it could help explain other gamma-ray bursts that don’t fit our understanding of where they come from.
“This is a remarkable GRB,” said Benjamin Gomberts. “We didn’t expect the mergers to last more than two seconds. Somehow, it drove the jet for almost a minute. This behavior could be explained by a long-lived neutron star, but what we saw cannot rule out a neutron star being ripped apart by a black hole.
“Studying more of these events will help determine what the correct answer is, and the detailed information we obtained from GRB 211211A will be invaluable to this explanation.”
Scientists hope that a switch-on of the James Webb Space Telescope will provide a better view of kilonovae. That telescope can capture images of distant astronomical objects and “sniff” their atmospheres, allowing us to see what elements are present through a process called spectroscopy.
“Unfortunately, even the best ground-based telescopes are not sensitive enough to perform spectroscopy,” Rustinejad said. “With JWST, we can have a spectrum of kilonovae. Those spectral lines provide direct evidence that you’ve detected very heavy elements.